My 85 had a 8.8 swap and I didn't know. Already got parts for the 7.5! What TO DO?

[IndyBill]

Welp, I'm re-doing my 85 GT and I pulled the rear end out of it a couple weeks ago assuming it was a 7.5. I tore it all apart not really looking at the details, I threw the differential in a bucket for cleaning and took the housing to have it blasted. While doing all that I ordered new spiders and clutches for it and a rebuild kit. Since this is going back stock and used as a cruiser I didn't care to swap in a 8.8.

I went out tonight and put the carrier / ring gear up on my bench and after dropping the ring gear off I looked for markings. I noticed 8-410 stamped on it and I thought it looked big. I measured across the gear and it is an 8.8. Its a 4.10 as it has 41 teeth and the pinion has 10 teeth.

UGH! I already bought everything to rebuild my 7.5 with a 3.40 gear and I don't want to hassle returning the stuff and losing money on shipping. I don't know if I want to store the 8.8 and maybe rebuild it later or sell it disassembled. I'm not even sure what an 8.8 is worth with 410 gears.

Any suggestions?

[massacre]

Is your diff 28 or 31 spline?

[IndyBill]

It's a 28 spline.

[wbrockstar]

For future reference,the quickest way to id each differential is by the shape of each cover.
A 7.5 cover has a flat top & bottom and rounded sides.
A 8.8 cover has a flat top & bottom,flat sides & rounded corners.

[massacre]

That sucks man
we all make mistakes
try not to beat yourself up
just adjust and overcome

[conmech]

Lesson learned. Either return it or list it in the classifieds section here. Either way, a slight hassle with potential of some cash loss.

[mudgepondexpress]

Never go backwards! Stay with the 8.8 and take the $ hit. Even the best 7.5 doesn't hold up that well under torque.

Kenny

[Mgino757]

I would stay with the 8.8" unless you're shooting for a concourse style restoration. Just sell the parts you've got if you're dead set on not returning them. My '85 is just a street cruiser, but I wouldn't take a 7.5" even if someone gave it to me for free.

[massacre]

If the parts are new, I don’t see why you can’t return them? You might take a small hit on a restocking fee but if you explain the situation you might hurt your pride a little but at least you’ll get most of your money back.

[IndyBill]

Yeah, I'm going back to stock with this car. Not worried about breaking the 7.5 this won't hit the track. Back in the mid-90's I had an 85 with 150 shot of nitrous and BF Goodrich Drag Radials with no problems. I put the 8.8 on a couple of FB parts pages last night for $300 and have it sold. Odd going back to 7.5 but......

[massacre]

Awesome, glad it all worked out.